package sort;

import java.util.Arrays;

public class MergeSort {
	public static void merge(int[] a, int low, int mid, int high) {
		int[] temp = new int[high - low + 1];
		int i = low;// 左指针
		int j = mid + 1;// 右指针
		int k = 0;
		// 把较小的数先移到新数组中
		while (i <= mid && j <= high) {
			if (a[i] < a[j]) {
				temp[k++] = a[i++];
			} else {
				temp[k++] = a[j++];
			}
		}
		// 把左边剩余的数移入数组
		while (i <= mid) {
			temp[k++] = a[i++];
		}
		// 把右边边剩余的数移入数组
		while (j <= high) {
			temp[k++] = a[j++];
		}
		// 把新数组中的数覆盖nums数组
		for (int k2 = 0; k2 < temp.length; k2++) {
			a[k2 + low] = temp[k2];
		}
	}

	public static void mergeSort(int[] a, int low, int high) {
		int mid = (low + high) / 2;
		if (low < high) {
			// 左边
			mergeSort(a, low, mid);
	//		System.out.print(" 处理左边:"+low+"到"+mid);
			// 右边
			mergeSort(a, mid + 1, high);
	//		System.out.print(" 处理右边:"+(mid+1)+"到"+high);
			// 左右归并
			merge(a, low, mid, high);
	//		System.out.print(" 左右归并:"+(low)+"到"+high);
	//		System.out.println(Arrays.toString(a));
		}
	}
	public static void mergeSort(int[] a){
		mergeSort(a, 0, a.length - 1);
	}
	public static void main(String[] args) {
		int a[] = { 5, 4, 2, 8, 6, 9, 1, 3, 7, 0};
		System.out.println("初始数据: "+Arrays.toString(a));
		mergeSort(a);
		System.out.println("排序结果：" + Arrays.toString(a));
	}
}
